Resonant Load Research Articles

Response of pavement and stratified ground due to vehicle loads considering rise of water table

ABSTRACTA two-dimensional model has been developed to investigate the dynamic response of pavement–embankment–subsoil system considering the rise of water table. The ground consists of pavement, embankment, topsoil, saturated soil under the natural water table and semi-infinite substratum. Above the natural water table, the material is assumed to be dry and viscoelastic. Below the natural water table, the soil is saturated and modelled as poroviscoelasitc material. The semi-infinite substratum is assumed to be water-resistant and taken as a viscoelastic half-space. When the water table rises, the submerged part is then saturated and taken as poroviscoelastic medium. Biot’s theory and Fourier transform are employed to describe the problem, and some improvements are made based on traditional stiffness matrix method to give semi-analytical solution to the problem. The solution has been verified using a simplified problem reported by existing research. The influences of load characteristics and rise of water table are investigated. Resonance load frequency exists, at which the maximum surface vertical displacement of the pavement reaches its largest value. The rise of water table decreases the resonance frequency and generally increases the maximum surface vertical displacement of the pavement. The pore water pressure and pore water velocity are also substantially affected by the rise of water table. In general, the rise of water table has an amplifying effect on the vibration of the pavement system and increases the damage risk, which needs to be considered in the design and maintenance of highways.

Investigation of the performances of PZT vs rare earth (BaLaTiO3) vibration based energy harvester

This study proposes the investigation of two piezoelectric material namely PZT and Lanthanum Doped Barium Titanate (BaLaTiO3 ) performance as a vibration based energy harvester. The piezoelectric material when applied mechanical stress or strain produces electricity through the piezoelectric effect. The vibration energy would exude mechanical energy and thus apply mechanical force on the energy harvester. The energy harvester would be designed and simulated using the piezoelectric material individually. The studied outputs are divided to frequency response, the load dependence, and the acceleration dependence whereby measurement are observed and taken at maximum power output. The simulation is done using the cantilevers design which employs d31 type of constants. Three different simulations to study the dependence of output power on the resonant frequency response, load and acceleration have found that material that exhibit highest power generation was the BaLaTiO3 .

Investigation of load transfer along interfaces of jacketed square columns

This study deals with a numerical investigation of load transfer along interfaces of jacketed columns using finite element models. Appropriate plasticity and constitutive models are used to simulate the response of concrete and steel bars. Experimental data were used to calibrate the simulation of mechanical characteristics. The different compressive strength of core and jacket concrete, the confinement ratio, the dowels\'s diameter size and the load pattern shapes were considered. The path diagrams along the interfaces elucidate the areas around the dowel bars where due to stress concentration plastic hinges and intense discontinuities are created. The stress flow also depicts the contribution of confinement of the jacketed area to the overall resonant load capacity of the core column. The scope of the research is to identify and quantify the shear transfer along the interfaces of strengthened elements.

Experimental analysis of pre-compressed circular cylindrical shell under axial harmonic load

In this paper the nonlinear dynamics of circular cylindrical shells under axial static (compressive) and periodic resonant loads have been experimentally investigated, the goal is to study the dynamic scenario and to analyze nonlinear regimes. A special test rig has been developed for the experiment in order to apply a static axial load combined with a dynamic axial load. The setup allows for investigating the linear behavior under static preload by means of the usual modal testing techniques; moreover, it allows for analyzing the nonlinear response which occurs when the dynamic axial load is periodic and gives rise to complex resonances. The complex dynamics, arising when a periodic axial load excites the asymmetric (shell like) modes, are analyzed by means of amplitude frequency diagrams, waterfall spectrum diagrams, bifurcation diagrams of Poincaré maps; a deep analysis of time histories, spectra, phase portraits and Poincaré maps completes the study of the complex dynamic scenario.

Broadband compact microstrip patch antenna design loaded by multiple split ring resonator superstrate and substrate

We present microstrip patch antenna loaded with multiple split ring resonator substrate and superstrate. We analyze how the loading of split ring resonator superstrate and substrate can improve the bandwidth compared to the simple microstrip patch antenna and microstrip patch antenna loaded with split ring resonator superstrate. Another important observation is made for multiple split ring resonator loading in superstrate and substrate of microstrip patch antenna. The design is compared for two, three, and four-ring split ring resonator loading. The designs are also compared for different gap spacing between the rings. All three designs are compared for small gap and large gap between the rings. The design results in the form of reflection coefficient and bandwidth is presented in this manuscript. The design results are also compared with previously published designs.

A Dual-Wideband CMOS LNA Using Gain–Bandwidth Product Optimization Technique

This paper presents a dual-wideband, common-gate, cascode low-noise amplifier (LNA) using gain---bandwidth product optimization technique. This approach shrinks the aspect ratio of the cascode MOS device, thereby reducing the equivalent parasitic capacitance of the resonator load to optimize the gain---bandwidth product of the LNA. The input impedance of the proposed LNA is analyzed, and the noise factor is well predicted through analytical equations. Measurement results that show well agreement with post-simulation results demonstrate the feasibility of this technique. In low-band mode, experimental results presented a maximum $$\left| S_{21} \right| $$S21 of 13.4 dB over a $$-$$-3-dB bandwidth of 3.1---4.8 GHz with a minimum noise figure of 4.5 dB. In high-band mode, the proposed LNA achieved a maximum $$\left| S_{21} \right| $$S21 of 13.6 dB with a minimum noise figure of 6.2 dB over a $$-$$-3-dB bandwidth of 7.3---9.4 GHz. A test chip with a die area of 0.83 mm$$^{2}$$2 was fabricated using a 0.18 $$\upmu $$μm CMOS process. The proposed dual-wideband LNA consumes 9.1 mW, excluding the buffer, from a supply voltage of 1.8 V.

Motor Irradiation According to the Concept of Proprioceptive Neuromuscular Facilitation: Measurement Tools and Future Prospects

The concept of Proprioceptive Neuromuscular Facilitation is widely used in the treatment of disorders of the musculoskeletal system. Among the basic principles, Motor Irradiation (MI) allows to activate weak muscles, by activating strong muscles. Despite being widely used, the neurophysiological basis that justify the Motor Irradiation and its measurement forms are not yet well understood, which motivated us to conduct a review of the databases of PubMed, Lilacs and Scielo, looking for articles that clarify the subject. The literature emphasizes three possible theories to justify MI, two neural and one biomechanical. There are several ways used to measure the MI, and the Electromyography, Functional magnetic resonance imaging and Load cell are the most cited in studies. Future studies could use the electroencephalography to measure the electrophysiological effects caused by strength irradiation in the Neuromuscular Facilitation Proprioceptive protocols.

Investigation of an integrative transverse-flux linear compressor

Purpose – The purpose of this paper is propose a novel integrative transverse-flux linear compressor (TFLC), which integrates compressor into a single-phase transverse-flux linear oscillating actuator with moving magnet. Its main merit is having similar lamination as rotate motor which is easy to be stacked. Design/methodology/approach – The simple lumped circuit model accounting for magnetic saturation, armature reaction and axial fringing effect is proposed. Based on this model, the magnetic field in air gap is calculated, and then the optimal PM height, PM length, split ratio and pole number are found. The predicted thrust force, stroke and system resonant frequency at no load are validated by prototype measurement. The relation of system resonant frequency and load are also measured. Findings – In this novel TFLC, the optimal split ratio is in area of 0.54∼0.56 and pole number is 6. For designed stroke 10 mm, suitable PM height and length are 3 mm and 63 mm, respectively. By measurement, the predicted thrust force, stroke and system resonant frequency at no load are validated. The measurement also shows that the system resonant frequency can be improved from 30 Hz of no load to 39 Hz at 0.7 Mpa air load. Originality/value – The novel TFLC has excellent driving performance and simple structure for maintenance. It can produce enough pressure to meet the requirement of refrigerator, so it is a strong candidate for refrigerating apparatus.

Enhanced Pulse-Density-Modulated Power Control for High-Frequency Induction Heating Inverters

This paper presents a 100-kW 100-kHz insulated-gate bipolar transistor (IGBT) series resonant inverter for induction heating applications that uses an improved power control scheme based on the standard pulse density modulation (PDM). This standard power control is a good solution for the design of high-frequency inverters because the output power factor is near to unity in a wide range of output power, resulting in great reduction of switching losses and electromagnetic noise. However, the output current can be in discontinuous mode, particularly for resonant loads of low quality factor or for low output power or low-load operation. This output current fluctuation produces a high output current ripple that can lead to an increase in power losses and loss of accuracy of the response of the frequency tracking control. The proposed control strategy, which is called enhanced PDM (EPDM), provides twice less output current ripple, thus resulting in an improved inverter behavior in terms of frequency tracking accuracy and energy efficiency. Experimental tests have been made, in order to compare the EPDM strategy with standard power control schemes.

A CPW‐fed triple band OCSRR embedded monopole antenna with modified ground for WLAN and WIMAX applications

ABSTRACTA coplanar waveguide fed triple band antenna is proposed for wireless local area network (WLAN) and worldwide interoperability for microwave access (WIMAX) applications. The proposed antenna consists of rectangle monopole with modified ground plane and open complementary split ring resonator (OCSRR) loading. The overall size of the antenna is 30 × 40 × 0.8 mm3, which provides Omnidirectional pattern in all three bands. The prototype of antenna is designed, fabricated, and measured. The measured −10 dB impedance bandwidths are 300 MHz (2.40–2.70 GHz), 680 MHz (3.32–4.00 GHz), and 1040 MHz (4.76–5.8 GHz) with resonance frequency at 2.6 GHz,3.4GHz, and 5GHz, respectively, which is suitable for WLAN/WiMAX applications. Parametric study on OCSRR is discussed to validate the results. Simulated and measured results of the antenna are presented and discussed. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2413–2418, 2015

Stabilization of gyrotron frequency by reflection from nonresonant and resonant loads

The possibility of stabilization of gyrotron frequency under the action of a wave reflected from a load (high-resonant or nonresonant) has been analyzed. The ranges of the system parameters that provide the most efficient frequency stabilization have been determined analytically and numerically.

The Variation Law of Mechanical Parameters of Type I Fatigue Crack Tip Under High Frequency Resonant Loading

This work explores the variation law of mechanical parameters at fatigue crack tip of compact tension specimen with type I pre-notch based on dynamic finite element method (FEM) in the high frequency resonant fatigue crack propagation test. The displacement fields, the strain fields and the stress intensity factors (SIF) at CT specimen fatigue crack tip in one stress cycle and at different crack lengths under constant amplitude high frequency sinusoidal alternating loading condition are calculated and the related variation laws of mechanical parameters are analyzed. In order to calculate the dynamic SIF at fatigue crack tip, the static SIF has been calculated first. The compared results of the static finite element analysis with the theoretical calculation show that finite element modeling and calculating method and respective results are accurate. Secondly, the variation law of SIF at crack tip during the process of fatigue crack propagation test is studied by dynamic FEM. Finally, the high frequency resonant fatigue crack propagation test has been performed and the dynamic strain gauge is used to measure the strain at crack tip during one stress cycle. The research results show that during crack stable propagation stage, the displacement, strain and SIF at type I fatigue crack tip are in the same form having high frequency resonant load, and the displacement, strain and SIF amplitude increase with the crack growth. The error of static SIF between the calculated result by FEM and the theoretical result is 2.51%. The maximum error of the strain at crack tip between the FEM calculating result and the experimental result is 2.93%.

The Measurement of the Fatigue Crack-Tip Displacement and Strain Fields under High Frequency Resonant Loading Applying DIC Method

In order to measure the displacement and strain field in the fatigue crack tip area of CT specimens under high frequency resonant loading condition in the fatigue crack propagation test, a method based on the digital image correlation (DIC) and digital high-speed photography technology are proposed in this paper. First, a series of digital speckle images of CT specimen under sinusoidal alternating load were collected by digital high-speed photography equipment, the displacement and strain fields within the region of crack tip in each image were calculated by DIC. The sinusoidal changing strain curve has been obtained by the least square sine wave fitting method, and the characteristic parameters of sinusoidal strain are calculated, such as the amplitude, frequency, phase, mean load . The images of characteristic position in one stress cycle were obtained by comparing the fitted sine curve of strain with the corresponding speckle images. Finally, the dynamic strain gauge was used to measure the strain at crack tip point during one stress cycle, and the accuracy and feasibility of DIC method were verified by the experimental results. The study result presented in this paper will supply a foundation for exploring the crack propagation law and measuring the fatigue crack growth parameters under high frequency resonant loading condition further.

Research on A Novel Modulation Strategy for Double Auxiliary Resonant Commutated Pole Soft-switching Inverter with the Shunt Dead Time

Aimed at the problem that the auxiliary commutation circuit (ACC) of auxiliary resonant commutated pole (ARCP) inverters has a high loss in commutation processes, this paper presents a novel modulation strategy with shunt dead time based on a double ARCP (DARCP) inverter. In comparison with the original modulation strategy, this modulation strategy cannot only achieve soft switching for all switches, but also avoid the superposition of resonance current and load current at commutation moments in double ACCs (DACCs) and make the maximum current through DACCs approximately equal to load current in commutation processes. So, the circulating current loss in DACCs and the current stress of auxiliary switches can be effectively reduced. According to the equivalent circuits in different operation modes under the novel modulation strategy, this paper analyzes the operation principle, soft-switching implementation condition, and optimal parameter design procedure of the DARCP inverter. Finally, a 10-kW–16-kHz DARCP inverter prototype with insulated gate bipolar transistor-based switches is built. Experimental results are given to demonstrate the validity and features of the DARCP inverter under the novel modulation strategy.

Buck-Boost Interleaved Inverter Configuration for Multiple-Load Induction Cooking Application

Induction cooking application with multiple loads need high power inverters and appropriate control techniques. This paper proposes an inverter configuration with buck-boost converter for multiple load induction cooking application with independent control of each load. It uses one half-bridge for each load. For a given dc supply of VDC, one more VDC is derived using buck- boost converter giving 2VDC as the input to each half-bridge inverter. Series resonant loads are connected between the centre point of 2 VDC and each half-bridge. The output voltage across each load is like that of a full-bridge inverter. In the proposed configuration, half of the output power is supplied to each load directly from the source and remaining half of the output power is supplied to each load through buck-boost converter. With buck-boost converter, each half-bridge inverter output power is increased to a full-bridge inverter output power level. Each half-bridge is operated with constant and same switching frequency with asymmetrical duty cycle (ADC) control technique. By ADC, output power of each load is independently controlled. This configuration also offers reduced component count. The proposed inverter configuration is simulated and experimentally verified with two loads. Simulation and experimental results are in good agreement. This configuration can be extended to multiple loads.

Wideband absorber at X‐band adopting trumpet‐shaped structures

A wideband single-layer absorber at X-band adopting trumpet structures is presented. One unit of the proposed absorber is composed of a trumpet-shaped resonator loading four chip resistors, a metallic backplane and an FR-4 (e r = 4.4-j0.02) substrate between them. The absorption is 99% at 10.9 GHz. The full width at half maximum is 95% at 12.7 GHz (6.7–18.7 GHz). The 90% absorption bandwidth is 65% at 12.75 GHz (8.6–16.9 GHz). The size of the unit cell is 5.6 × 5.6 × 2.4 mm3. The proposed absorber is almost insensitive to polarisations of incident waves due to the symmetry of the structure. The results of EM simulation and measurements are in good agreement.

Characteristic Research on Wireless Power Transfer Based on Magnetic Coupling Resonant

This paper analyses the working principle of magnetic coupling resonant wireless power transmission system based on mutual inductance coil model, and then gets the expressions of load power and transmission efficiency. By the theoretical analysis the relations between the various system parameters such as: coil size, transmission distance, load resistance, the resonant frequency and load power, transmission efficiency are obtained. According to the results of theoretical analysis, the system’s characteristics of load power and transmission efficiency with varying transmission distance are studied. Finally, simulations verify the accuracy of analysis by Matlab/Simulink.

Excitation of the resonant loads with the multi-vector synthesized si-nusoidal voltage decreases conduction losses and improves reliability

A method of DC/AC conversion based on the multi-vector synthesis of the sinusoidal voltage with the sequential elimination of unwanted harmonics in the output voltage and current resulting in lower power dissipation especially for the resonant loads is discussed. Simulation results of the standard 50% duty cycle operation approach and the proposed multi-vector topology are compared and linked to the temperature related characteristics of the MOSFET switches and resulting life expectancy of the DC/AC inverter.Ref.12, Figs. 6, tab.

Design of Metamaterial-Inspired Wideband Absorber at X-Band Adopting Trumpet Structures

This letter presents two types of metamaterial-inspired absorbers adopting resistive trumpet structures at the X band. The unit cell of the first type is composed of a trumpet-shaped resonator loading a chip resistor, a metallic back plane, and a FR4 (er = 4.4-j 0.02) substrate between them (single-layer). The absorption rate is 99.5% at 13.3 GHz. The full width at half maximum (FWHM) is 95 % at 11.2 GHz (from 5.9 to 16.5 GHz). The size of unit cell is 5.6×5.6×2.4 mm 3 . The second type has been optimized with a 7 Ω/square uniform resistive coating, removing the chip resistors but leading to results comparable to the first type. The proposed absorbers are almost insensitive to polarizations of incident waves due to symmetric geometry.

Gust durations, gust factors and gust response factors in wind codes and standards

This paper discusses the appropriate duration for basic gust wind speeds in wind loading codes and standards, and in wind engineering generally. Although various proposed definitions are discussed, the 'moving average' gust duration has been widely accepted internationally. The commonly-specified gust duration of 3-seconds, however, is shown to have a significant effect on the high-frequency end of the spectrum of turbulence, and may not be ideally suited for wind engineering purposes. The effective gust durations measured by commonly-used anemometer types are discussed; these are typically considerably shorter than the 'standard' duration of 3 seconds. Using stationary random process theory, the paper gives expected peak factors, g w, as a function of the non-dimensional parameter (T/τ), where T is the sample, or reference, time, and τ is the gust duration, and a non-dimensional mean wind speed, U. T/L w, where U is a mean wind speed, and L w is the integral length scale of turbulence. The commonly-used Durst relationship, relating gusts of various durations, is shown to correspond to a particular value of turbulence intensity I u, of 16.5%, and is therefore applicable to particular terrain and height situations, and hence should not be applied universally. The effective frontal areas associated with peak gusts of various durations are discussed; this indicates that a gust of 3 seconds has an equivalent frontal area equal to that of a tall building. Finally a generalized gust response factor format, accounting for fluctuating and resonant along-wind loading of structures, applicable to any code is presented.